Method for Autonomously Repairing Surface Defects in a Workpiece Through Surface Modifications

1. A method comprising: accessing a virtual model of a workpiece; accessing a nominal toolpath for the workpiece; accessing a nominal target force assigned to the nominal toolpath; accessing a first set of images depicting the workpiece; based on the first set of images, detecting a first defect in a first workpiece region of the workpiece; in response to characterizing the first defect as repairable via material removal from the workpiece, generating a repair toolpath for the first workpiece region based on a first geometry of the first workpiece region represented in the virtual model; during a repair cycle, via a set of actuators coupled to a sanding head, navigating the sanding head across the first workpiece region according to the repair toolpath; and during a processing cycle: accessing a first sequence of force values output by a force sensor coupled to the sanding head; and via the set of actuators: navigating the sanding head across the workpiece according to the nominal toolpath; and based on the first sequence of force values, deviating the sanding head from the nominal toolpath to maintain forces, applied by the sanding head to the workpiece, proximal the nominal target force.

2. The method of claim 1, further comprising: based on the first defect, assigning a target repair force, greater than the nominal target force, to the repair toolpath; and during the repair cycle: accessing a second sequence of force values output by the force sensor; and via the set of actuators: based on the second sequence of force values, deviating the sanding head from the repair toolpath to maintain forces, applied by the sanding head to the workpiece, proximal the target repair force.

3. The method of claim 2: wherein navigating the sanding head across the first workpiece region according to the repair toolpath during the repair cycle comprises navigating the sanding head across the first workpiece region according to the repair toolpath during a first time period; and wherein navigating the sanding head across the workpiece according to the nominal toolpath during the processing cycle comprises navigating the sanding head across the workpiece according to the nominal toolpath during a second time period succeeding the first time period.

4. The method of claim 1: wherein navigating the sanding head across the workpiece during the processing cycle comprises: navigating the sanding head within a second workpiece region of the workpiece and toward the first workpiece region according to the nominal toolpath during a first time period; and wherein accessing the first set of images comprises: in response to the sanding head reaching the first workpiece region during the first time period: pausing the processing cycle; and navigating an end effector, supporting the sanding head and an optical sensor, over the first workpiece region to capture the first set of images via the optical sensor; and further comprising: in response to pausing the processing cycle: initiating the repair cycle within the first workpiece region during a second time period succeeding the first time period; and in response to completion of the repair cycle within the first workpiece region during the second time period: resuming the processing cycle during a third time period succeeding the second time period.

5. The method of claim 1: wherein generating the repair toolpath comprises generating the repair toolpath defining a boustrophedonic geometry contained within the first workpiece region and spanning the first defect; wherein navigating the sanding head across the first workpiece region during the repair cycle comprises navigating the sanding head within the first workpiece region; wherein accessing the nominal toolpath for the workpiece comprises accessing the nominal toolpath for the workpiece spanning the first workpiece region and a second workpiece region of the workpiece; and wherein navigating the sanding head across the workpiece during the processing cycle comprises navigating the sanding head across the first workpiece region and the second workpiece region.

6. The method of claim 1: further comprising: accessing a nominal feed rate assigned to the nominal toolpath; and accessing a repair feed rate, less than nominal feed rate, specified for defects; wherein navigating the sanding head across the first workpiece region during the repair cycle comprises: navigating the sanding head along the repair toolpath at the nominal feed rate; and in response to the sanding head approaching the first defect, navigating the sanding head along the repair toolpath at the repair feed rate; and wherein navigating the sanding head across the workpiece during the processing cycle comprises navigating the sanding head across the workpiece at the nominal feed rate.

7. The method of claim 1: further comprising navigating an optical sensor over and offset from the workpiece during a global scan cycle; wherein accessing the first set of images depicting the workpiece comprises accessing the first set of images, characterized by a first resolution, captured by the optical sensor during the global scan cycle; wherein accessing the virtual model of the workpiece comprises generating the virtual model of the workpiece based on the first set of images; wherein accessing the nominal toolpath for the workpiece comprises generating the nominal toolpath based on a geometry of the workpiece represented in the virtual model; and further comprising: in response to detecting the first defect in the first workpiece region of the workpiece based on the first set of images, navigating the optical sensor over and offset from the first workpiece region of the workpiece during a local scan cycle; accessing a second set of images, characterized by a second resolution greater than the first resolution, captured by the optical sensor during the local scan cycle; and based on the second set of images, characterizing the first defect as repairable via material removal from the workpiece.

8. The method of claim 7: further comprising: based on the first set of images, detecting a second defect indicator in a second workpiece region of the workpiece; in response to detecting the second defect in the second workpiece region of the workpiece, navigating the optical sensor over and offset from the second workpiece region of the workpiece during a second local scan cycle; accessing a third set of images, characterized by the second resolution, captured by the optical sensor during the second local scan cycle; and based on the third set of images, characterizing the second defect as irreparable via material removal from the workpiece; and in response to characterizing the second defect as irreparable via material removal from the workpiece: generating a notification to manually repair the second defect in the second workpiece region; and serving the notification to an operator; and wherein generating the nominal toolpath comprises generating the nominal toolpath excluding the second workpiece region.

9. The method of claim 7, further comprising, in response to characterizing the second defect as irreparable via material removal from the workpiece: annotating the virtual model with a location of the second defect on the workpiece; and rendering the virtual model on a display.

10. The method of claim 8: wherein characterizing the first defect as repairable via material removal from the workpiece comprises: extracting a first set of features from a first image, in the second set of images, depicting the first workpiece region of the workpiece; and characterizing the first defect as a paint sag based on the first set of features; and wherein characterizing the second defect as irreparable via material removal from the workpiece comprises: extracting a second set of features from a second image, in the third set of images, depicting the second workpiece region of the workpiece; and characterizing the second defect as a gouge based on the second set of features.

11. The method of claim 1: wherein accessing the first set of images comprises accessing the first set of images comprising depth maps captured by a depth sensor navigated over the workpiece; and wherein detecting the first defect comprises detecting the first defect based on a three-dimensional surface discontinuity, present in the first workpiece region of the workpiece, based on the first set of images.

12. The method of claim 1: wherein accessing the first set of images comprises accessing the first set of images comprising photographic images captured by a color camera sensor navigated over the workpiece; and wherein detecting the first defect comprises detecting the first defect based on a two-dimensional color discontinuity detected in a first photographic image, in the first set of images, depicting the first workpiece region of the workpiece.

13. The method of claim 1, further comprising: characterizing the first defect indicator as the first defect of a first defect type based on features detected in the second set of images; annotating the virtual model with: the first defect type at a location of the first defect; and characteristics of the repair toolpath. further comprising navigating an optical sensor over and offset from the workpiece during a scan cycle; wherein accessing the first set of images depicting the workpiece comprises accessing the first set of images comprising photographic images captured by the optical sensor during the global scan cycle; wherein detecting the first defect in the first workpiece region of the workpiece based on the first set of images comprises: extracting a first set of features depicting the first workpiece region of the workpiece from the first set of images; detecting the first defect based on the first set of features; characterizing a first size of the first defect based on the first set of features; and characterizing a first severity of the first defect proportional to the first size; further comprising: extracting a second set of features depicting a second workpiece region of the workpiece from the first set of images; detecting a second defect in the second workpiece region of the workpiece based on the second set of features; and characterizing a second size, less than the first size, of the second defect based on the second set of features; and characterizing a second severity, less than the first severity, of the second defect proportional to the second size; wherein generating the repair toolpath for the first workpiece region comprises generating the repair toolpath for the first workpiece region further in response to the first severity exceeding a threshold severity; and wherein accessing the nominal toolpath for the workpiece comprises, in response to the second severity score falling below the threshold severity, generating the nominal toolpath, spanning the second workpiece region and a third workpiece region of the workpiece, based on a geometry of the workpiece represented in the virtual model.

14. A method comprising: accessing a virtual model of a workpiece; accessing a first image depicting a first workpiece region of the workpiece; based on the first image, detecting a first defect in the first workpiece region of the workpiece; in response to characterizing the first defect as repairable via material removal from the workpiece, generating a first toolpath for the first workpiece region based on a first geometry of the first workpiece region represented in the virtual model; accessing a second toolpath for a second workpiece region of the workpiece; accessing a nominal target force assigned to the workpiece; during a repair cycle, via a set of actuators coupled to a sanding head, navigating the sanding head across the first workpiece region according to the first toolpath; and during a processing cycle: accessing a sequence of force values output by a force sensor coupled to the sanding head; and via the set of actuators: navigating the sanding head across the second workpiece region of the workpiece according to the second toolpath; and based on the sequence of force values, deviating the sanding head from the second toolpath to maintain forces, applied by the sanding head to the second workpiece region of the workpiece, proximal the nominal target force.

15. The method of claim 14, further comprising: based on the first defect, assigning a target repair force, greater than the nominal target force, to the repair toolpath; and during the repair cycle: accessing a second sequence of force values output by the force sensor; and via the set of actuators: based on the second sequence of force values, deviating the sanding head from the repair toolpath to maintain forces, applied by the sanding head to the workpiece, proximal the target repair force.

16. The method of claim 14: wherein navigating the sanding head across the second workpiece region during the processing cycle comprises: navigating the sanding head within the second workpiece region of the workpiece and toward the first workpiece region according to the nominal toolpath during a first time period; wherein accessing the first set of images comprises: in response to the sanding head reaching the first workpiece region during the first time period: pausing the processing cycle; and navigating an end effector, supporting the sanding head and an optical sensor, over the first workpiece region to capture the first set of images via the optical sensor; and further comprising: in response to pausing the processing cycle: initiating the repair cycle within the first workpiece region during a second time period succeeding the first time period; and in response to completion of the repair cycle within the first workpiece region during the second time period: resuming the processing cycle during a third time period succeeding the second time period.

17. The method of claim 14: further comprising navigating an optical sensor over and offset from the workpiece during a global scan cycle; wherein accessing the first set of images depicting the workpiece comprises accessing the first set of images, characterized by a first resolution, captured by the optical sensor during the global scan cycle; wherein accessing the virtual model of the workpiece comprises generating the virtual model of the workpiece based on the first set of images; wherein accessing the nominal toolpath for the workpiece comprises generating the nominal toolpath based on a geometry of the workpiece represented in the virtual model; and further comprising: in response to detecting the first defect in the first workpiece region of the workpiece based on the first set of images, navigating the optical sensor over and offset from the first workpiece region of the workpiece during a local scan cycle; accessing a second set of images, characterized by a second resolution greater than the first resolution, captured by the optical sensor during the local scan cycle; and based on the second set of images, characterizing the first defect as repairable via material removal from the workpiece.

18. A method comprising: accessing a virtual model of a workpiece; accessing a first image depicting a first workpiece region of the workpiece; based on the first image, detecting a first defect in the first workpiece region of the workpiece; in response to characterizing the first defect as repairable via material removal from the workpiece: generating a first toolpath for the first workpiece region based on a first geometry of the first workpiece region represented in the virtual model; and assigning a target repair force to the first toolpath; accessing a second toolpath for a second workpiece region of the workpiece; and during a processing cycle: accessing a sequence of force values output by a force sensor coupled to a sanding head; and via a set of actuators coupled to the sanding head: navigating the sanding head across the first workpiece region of the workpiece according to the first toolpath; and based on the sequence of force values, deviating the sanding head from the first toolpath to maintain forces, applied by the sanding head to the first workpiece region of the workpiece, proximal the target repair force; and via the set of actuators, navigating the sanding head across the second workpiece region according to the second toolpath.

19. The method of claim 18: further comprising navigating an optical sensor over and offset from the workpiece during a global scan cycle; wherein accessing the first set of images depicting the workpiece comprises accessing the first set of images, characterized by a first resolution, captured by the optical sensor during the global scan cycle; and wherein accessing the virtual model of the workpiece comprises generating the virtual model of the workpiece based on the first set of images.

20. The method of claim 18, wherein accessing the sequence of force values comprises accessing the sequence of force values, output by the force sensor, representing forces applied by the sanding head to the workpiece parallel to an axis of rotation of the sanding head.